Why is my iMac slow after rebooting?
February 25, 2020 11:07 AM   Subscribe

When I reboot my iMac, it's basically unusable for 10-15 minutes after it restarts.

I have a Late 2015 27" iMac 15 with 16 gigs of RAM and 40 gb free hard drive space on the startup drive. It runs fine, but on the occasion that things get mucked up and I need to restart, there's often something that takes forever to quit, and then when it finally restarts, I can barely do anything for 10-15 minutes — and then all of a sudden it's fine. It's running the latest version of Catalina, but I've had the same issue on previous OSs. I've run Disk Utility from Restore mode and it doesn't find anything wrong, and Googling has turned up nothing.

I have a slightly older (but faster) iMac at work running the same version of Catalina, and it never exhibits this problem.
posted by jonathanhughes to Computers & Internet (8 answers total) 2 users marked this as a favorite
Is your iMac using an SSD or regular hard drive? If it's using an HDD and your work system has an SSD, that would probably account for the slowness on startup. Might also be running a bunch of startup items on your personal mac?

You could also try running first aid on your disk and see if it finds any problems.
posted by jzb at 11:21 AM on February 25, 2020

Does this happen if you reboot when things are behaving normally? Do you know what gets 'mucked up'?

When it does happen, use activity monitor to see what is running (before if possible, and) after reboot and what processes are using lots of CPU. Also check for high disk IO and network IO

I would suspect one of the programs which is reopened when you reboot. E.g. a browser with lots of open tabs.
posted by epo at 11:37 AM on February 25, 2020

Google Chrome was often the culprit for me in the past - it's an absolute RAM hog, especially when starting cold, trying to restore a bunch of tabs and especially when one of those tabs crashed/ran out of control and caused the need for the reboot in the first place.

These days, Firefox is a very capable and fast browser (they've re-engineered it and it is very zippy) and Safari is sometimes even faster.
posted by Happy Dave at 12:44 PM on February 25, 2020 [2 favorites]

Mac user here. My gut says stick to Safari. I've had issues like Happy Dave mentions with Chrome especially. I just stopped using Chrome and Firefox.
posted by SoberHighland at 2:57 PM on February 25, 2020

Response by poster: I'm generally work doing work in Logic before things get mucked up, but there's never any particular thing. Things just get slow all of a sudden — and not necessarily within Logic, but in the finder and Safari. I tend to have lots of virtual instruments with large sample libraries loaded, so I imagine that Logic may be using up so much memory that the other things can't work.

I generally do have Safari open with several windows and tabs, but not a massive amount. I generally don't use Chrome for much, so that's not the culprit.

I restart after things were working fine was pretty quick (the only thing that slowed it down as far as I could tell was the software for my audio interface loading).

It seems like the open windows in Safari could be a culprit, but generally, I'm able to quit out of it after things get mucky, but before I restart, so I can't figure out why it would take up so many resources after a restart (especially when it's not launching on startup).
posted by jonathanhughes at 6:40 PM on February 25, 2020

Best answer: I would try and get Activity Monitor running while it is being slow to see what’s running and taking a lot of CPU or doing a lot of I/O. It could be something like Spotlight or a backup system reindexing things at startup.
posted by jimw at 11:22 PM on February 25, 2020

Response by poster: Good idea! I'll try that.
posted by jonathanhughes at 4:16 AM on February 26, 2020

I've found having an out-of-date version of DropBox will turn our Mac laptops into glaciers. Reinstalling with the latest version usually fixes the problem, at least temporarily.
posted by xiix at 11:56 AM on February 26, 2020

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